Well I am not using the arduino board itself so the onboard regulator isn't really my concern. But either way, I can't use USB power alone because I need higher current to run a few servos.
I have a few LM317 regulators around - would that work? A quick schematic of what I was thinking about:
J1 is a 3.7V output for the tablet
J2 is 5V output for the arduino
If I wired things like this, would the power be only drawn from the DC power source? Or would it draw power from the li-po too?